<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>奔跑的北极熊</title>
</head>
<style>
    h1 {
        height: 100px;
        line-height: 150px;
        text-align: center;
    }

    .wbear {
        position: absolute;
        width: 200px;
        height: 100px;
        bottom: 0px;
        background-image: url(./img/bear.png);
        /* 第一个动画为北极熊自身图片滚动（分为8步），第二个动画为北极熊整体的移动 */
        animation: bear .8s steps(8) infinite, bearmove 15s forwards;
    }

    @keyframes bear {
        0% {
            background-position: 0 0;
        }

        100% {
            background-position: -1600px 0;
        }
    }

    @keyframes bearmove {
        0% {
            left: 0;
        }

        100% {
            left: 50%;
            transform: translateX(-50%);
        }
    }

    .bg1 {
        position: relative;
        height: 400px;
        background-image: url(./img/bg2.png);
        animation: bgmove1 30s linear alternate infinite ;
    }

    .bg2 {
        position: absolute;
        width: 100%;
        height: 200px;
        left: 0px;
        bottom: 0px;
        background-image: url(./img/bg1.png);
        animation: bgmove2 30s linear alternate infinite;
    }

    @keyframes bgmove1 {
        0% {
            background-position: 0 0;
        }

        100% {
            background-position: -400px 0;
        }
    }

    @keyframes bgmove2 {
        0% {
            background-position: 0 0;
        }

        100% {
            background-position: -1600px 0;
        }
    }
</style>

<body>
    <h1>CSS3动画——奔跑的北极熊</h1>

    <div class="bg1">
        <div class="bg2">
            <div class="wbear"></div>
        </div>
    </div>
</body>

</html>
